For 10 hours Wednesday, Sydney time, schoolgirl Madeleine Pulver sat terrified and transfixed in her family home as police and bomb disposal experts worked to free her from what they believed was “a collar bomb,” never before seen in Australia.

Police said they faced an unprecedented situation, both “extremely complex and stressful,” given that the device was thought to be a remotely detonated bomb, or one capable of being activated by a trembler switch. The trembler switch has been used by the Provisional IRA and other terrorist groups to detonate car bombs from safe distances. They can be set off when the explosive device is tilted beyond a certain angle.

At midnight last night, the device was found to be “a very, very elaborate hoax,” possibly part of an extortion attempt against the young woman’s family.

“[The hoax] certainly gave the appearance of a legitimate improvised explosive device,” New South Wales Police Assistant Commissioner Mark Murdoch told reporters. “We had to treat it seriously until we could prove otherwise, and that’s exactly what we did, and that’s why it took so long.”

According to the Sydney Daily Telegraph, the intruder entered the Pulver family’s harborside home shortly after 2 p.m., and ordered the terrified teenager to the front of the house, where she was forced to sit down as the device was strapped to her neck. Some reports said it was tethered to her with a chain.

As the masked intruder did his work, he told his hostage she would be allowed to call the police once he’d left. He warned her that if she provided details of either him or their conversation, he would activate the explosive. He cautioned her that he’d also planted a listening device in the home so he could hear what she said to police. He then left, reportedly attaching a ransom note to the device.

Madeleine Pulver celebrated her 18th birthday last month and is in her final year at the prestigious all-girls high school, Wenona, on Sydney’s exclusive north shore. She is due to begin her final exams in two months.

Her father, William Pulver, a high-profile business executive and one of Sydney’s wealthiest men, is the CEO of Appen Butler Hill, a linguistic-solutions company that provides linguistic and voice-recognition services in more than 120 languages to most of the world’s automated telephone call center and in-car navigation systems. The company’s clients include Toshiba, Microsoft, Google, IBM and Fujitsu, as well as governmental bodies such as the U.S. Defense Department.

Until recently, William Pulver and his wife, Belinda, were based in New York, where he was president and chief executive of the global research firm, NetRatings, before returning to their plush four-bedroom home overlooking Sydney Harbor. Among their neighbors in this elite, leafy suburb are wealthy and prominent figures from the business and sporting worlds.

Wednesday night, the street was cordoned off as police and bomb specialists tried to determine whether the device was real or fake. Murdoch said it had been fastened to Madeleine “by a chain or something similar,” and that this had seriously complicated efforts to remove it. It also had prolonged Madeleine Pulver’s extreme trauma.

Police were called to the Pulver home shortly before 2.30 p.m. (Australian Eastern Standard Time) after William Pulver received a frantic phone call from his daughter. Nearby residents were evacuated immediately while bomb technicians, negotiators and detectives were called to the scene.

You would never expect it to happen in real life in Australia.

Murdoch praised the courage and poise of a young policewoman who arrived first on the scene with a male colleague. As the policeman summoned help and evacuated the street, the female officer went into the house to sit with the teenager.

“She was not wearing any protective clothing,” Murdoch said. “She wasn’t trained as a negotiator, but she made the decision herself, this young officer, to stay with Madeleine and make sure she tried to remain calm and she wasn’t left alone. She did an outstanding job in that regard.”

During the 10-hour operation, New South Wales police sought advice from British military experts and the Australian Federal Police as they worked to make the device safe. While they did so, Madeleine’s parents stood outside the house and communicated with their daughter through police officers.

Murdoch stated the obvious when he said Madeleine’s parents were “clearly and understandably very upset by what had happened.

“They were very, very concerned for their daughter as any parent would be. They were at a loss to explain why them, why they’d been … why this had happened to them as opposed to anyone else.”

During her ordeal, Madeleine was in “an uncomfortable position,” unable to move, and was given food and water and kept warm by the police. Shortly before midnight (AEST), she was released from the device by bomb specialists and taken to hospital. She was reunited with her parents a few hours later.

A major manhunt is underway for the person or persons responsible for the incident, with the device itself possibly offering the best clue. Roy Ramm, a former commander of specialist operations with Scotland Yard’s hostage-response team, told Australian media that police almost certainly would be looking at the device for DNA.

“There’ll be a really detailed forensic examination of this device to see if there’s any DNA on it, to see if it might match DNA held in any databases,” he said. Police no doubt also would look at Madeleine Pulver’s movements in the hours before she was taken hostage, including CCTV footage, to determine whether she’d been followed.

Australian Prime Minister Julia Gillard expressed her disbelief over the teenager’s ordeal, likening it to something out of Hollywood. “When I looked at it this morning the first thing I said was, 'It's like a Hollywood script, the kind of thing you would see at the cinema or on TV'," she told a Perth radio station. "You would never expect it to happen in real life in Australia."